There’s lots of buzz about lossless audio formats (well, not literally). Why should you care and why does it matter for your home theater? Why are lossless audio formats such as Dolby TrueHD and DTS Master Audio superior to their DVD predecessors?
Well, it all started when sound went digital. One of the first instances of this was the audio CD. Unlike your old records which represented music with physical grooves, digital music is represented by a series of 1s and 0s. The more 1s and 0s you have, the more accurate the sound recording is and in turn the more computer memory or disk space you need to store it. Computer memory used to be much more expensive so great minds came up with the idea of compressing audio. In another words, they found a way to cheat and not store all of the 1s and 0s by using complex math. For example, a silent part of a recording is probably represented by mostly 0s but the mathematical algorithm removes the need to store all of the 0s seperately. The downside is when the math is reversed, some of the information is not recovered and it doesn’t sound as good as the original. Audio compression that does this is known as a “lossy” format. MP3, which is an example of a lossy format, compresses the songs down so less disk space or memory is needed. This is why you can burn hours of MP3 songs on a data CD but an audio CD can only hold about an hour of music (audio CD music is uncompressed). Lossy formats such as MP3 have improved over time and it’s sometimes hard to tell the difference between that and the uncompressed recording especially when you are on a loud train with your headphones.
However, by definition, lossy formats do not contain all of the information from the original recording. In response, lossless formats were developed. They used even more complex math to save space but they don’t lose any information along the way (simlar to “zipping a file”). These formats required blu-ray’s high capacity to provide the necessary space to store all of the information required. BTW, blu-ray has five times the space that DVD provided for audio. Alternatively, this also allows blu-ray to hold an uncompressed audio format known as LPCM which is used in audio CDs as well.
In addition to lossless audio, TrueHD and DTS Master Audio are also superior since they offer up to 8 separate tracks of high fidelity audio.
While blu-ray supports TrueHD, it does NOT require it. Some blu-ray disks still use the AC3 Dolby Digital format used on DVDs. Here’s a sampling from my own blu-ray collection and what tracks they have: The newest Star Trek movie and The Dark Knight have Dolby TrueHD 24-bit tracks. Terminator Salvation and Watchmen have DTS Master Audio tracks. 2001: A Space Odyssey has a LPCM track. If you want to see the comprehensive directory of what type of soundtrack each blu-ray disk on the market has click here. You will see that some blu-rays just have the standard Dolby Digital track.
At the end of the day, is there really a discernable difference between TrueHD and Dolby Digital? Is it a good reason to upgrde to blu-ray? This article states that one cannot tell the difference. My experience with The Dark Knight says YES, there is a BIG difference. Why the disagreement? One theory for this is the regular Dolby Digital tracks on a blu-ray disk are taken from an inferior source. Whatever the reason, it does not change the fact that TrueHd and DTS Master Audio kick ass.